Earlier used to post the current command without checking queue full
     after backlog submissions. So, post the current command only after
     confirming the space in queue after backlog submissions.

     Maintain host write index instead of reading device registers
     to get the next free slot to post the command.

     Return -ENOSPC in queue full case.
Signed-off-by: NSrikanth Jampala <Jampala.Srikanth@cavium.com>
Reviewed-by: NGadam Sreerama <sgadam@cavium.com>
Tested-by: NJha, Chandan <Chandan.Jha@cavium.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This patch fixes sleep-in-atomic bugs in AES-CBC and AES-XTS VMX
implementations. The problem is that the blkcipher_* functions should
not be called in atomic context.

The bugs can be reproduced via the AF_ALG interface by trying to
encrypt/decrypt sufficiently large buffers (at least 64 KiB) using the
VMX implementations of 'cbc(aes)' or 'xts(aes)'. Such operations then
trigger BUG in crypto_yield():

[  891.863680] BUG: sleeping function called from invalid context at include/crypto/algapi.h:424
[  891.864622] in_atomic(): 1, irqs_disabled(): 0, pid: 12347, name: kcapi-enc
[  891.864739] 1 lock held by kcapi-enc/12347:
[  891.864811]  #0: 00000000f5d42c46 (sk_lock-AF_ALG){+.+.}, at: skcipher_recvmsg+0x50/0x530
[  891.865076] CPU: 5 PID: 12347 Comm: kcapi-enc Not tainted 4.19.0-0.rc0.git3.1.fc30.ppc64le #1
[  891.865251] Call Trace:
[  891.865340] [c0000003387578c0] [c000000000d67ea4] dump_stack+0xe8/0x164 (unreliable)
[  891.865511] [c000000338757910] [c000000000172a58] ___might_sleep+0x2f8/0x310
[  891.865679] [c000000338757990] [c0000000006bff74] blkcipher_walk_done+0x374/0x4a0
[  891.865825] [c0000003387579e0] [d000000007e73e70] p8_aes_cbc_encrypt+0x1c8/0x260 [vmx_crypto]
[  891.865993] [c000000338757ad0] [c0000000006c0ee0] skcipher_encrypt_blkcipher+0x60/0x80
[  891.866128] [c000000338757b10] [c0000000006ec504] skcipher_recvmsg+0x424/0x530
[  891.866283] [c000000338757bd0] [c000000000b00654] sock_recvmsg+0x74/0xa0
[  891.866403] [c000000338757c10] [c000000000b00f64] ___sys_recvmsg+0xf4/0x2f0
[  891.866515] [c000000338757d90] [c000000000b02bb8] __sys_recvmsg+0x68/0xe0
[  891.866631] [c000000338757e30] [c00000000000bbe4] system_call+0x5c/0x70

Fixes: 8c755ace ("crypto: vmx - Adding CBC routines for VMX module")
Fixes: c07f5d3d ("crypto: vmx - Adding support for XTS")
Cc: stable@vger.kernel.org
Signed-off-by: NOndrej Mosnacek <omosnace@redhat.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Commit 71e52c27 ("crypto: arm64/aes-ce-gcm - operate on
two input blocks at a time") modified the granularity at which
the AES/GCM code processes its input to allow subsequent changes
to be applied that improve performance by using aggregation to
process multiple input blocks at once.

For this reason, it doubled the algorithm's 'chunksize' property
to 2 x AES_BLOCK_SIZE, but retained the non-SIMD fallback path that
processes a single block at a time. In some cases, this violates the
skcipher scatterwalk API, by calling skcipher_walk_done() with a
non-zero residue value for a chunk that is expected to be handled
in its entirety. This results in a WARN_ON() to be hit by the TLS
self test code, but is likely to break other user cases as well.
Unfortunately, none of the current test cases exercises this exact
code path at the moment.

Fixes: 71e52c27 ("crypto: arm64/aes-ce-gcm - operate on two ...")
Reported-by: NVakul Garg <vakul.garg@nxp.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: NVakul Garg <vakul.garg@nxp.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

A regression was reported bisecting to 1476db2d
"Move HashKey computation from stack to gcm_context".  That diff
moved HashKey computation from the stack, which was explicitly aligned
in the asm, to a struct provided from the C code, depending on
AESNI_ALIGN_ATTR for alignment.   It appears some compilers may not
align this struct correctly, resulting in a crash on the movdqa
instruction when attempting to encrypt or decrypt data.

Fix by using unaligned loads for the HashKeys.  On modern
hardware there is no perf difference between the unaligned and
aligned loads.  All other accesses to gcm_context_data already use
unaligned loads.
Reported-by: NMauro Rossi <issor.oruam@gmail.com>
Fixes: 1476db2d ("Move HashKey computation from stack to gcm_context")
Cc: <stable@vger.kernel.org>
Signed-off-by: NDave Watson <davejwatson@fb.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

call chtls_free_uld() only for the initialized cdev,
this fixes NULL dereference in chtls_free_uld()
Signed-off-by: NGanesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: NAtul Gupta <atul.gupta@chelsio.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

ARMv8.2 specifies special instructions for the SM3 cryptographic hash
and the SM4 symmetric cipher. While it is unlikely that a core would
implement one and not the other, we should only use SM4 instructions
if the SM4 CPU feature bit is set, and we currently check the SM3
feature bit instead. So fix that.

Fixes: e99ce921 ("crypto: arm64 - add support for SM4...")
Cc: <stable@vger.kernel.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Crypto engine needs some temporary locations in external memory for
running RSA decrypt forms 2 and 3 (CRT).
These are named "tmp1" and "tmp2" in the PDB.

Update DMA mapping direction of tmp1 and tmp2 from TO_DEVICE to
BIDIRECTIONAL, since engine needs r/w access.

Cc: <stable@vger.kernel.org> # 4.13+
Fixes: 52e26d77 ("crypto: caam - add support for RSA key form 2")
Fixes: 4a651b12 ("crypto: caam - add support for RSA key form 3")
Signed-off-by: NHoria Geantă <horia.geanta@nxp.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

xts setkey callback returns 0 on some error paths.
Fix this by returning -EINVAL.

Cc: <stable@vger.kernel.org> # 4.12+
Fixes: b189817c ("crypto: caam/qi - add ablkcipher and authenc algorithms")
Signed-off-by: NHoria Geantă <horia.geanta@nxp.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Descriptor address needs to be swapped to CPU endianness before being
DMA unmapped.

Cc: <stable@vger.kernel.org> # 4.8+
Fixes: 261ea058 ("crypto: caam - handle core endianness != caam endianness")
Reported-by: NLaurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: NHoria Geantă <horia.geanta@nxp.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Enhance the GHASH implementation that uses 64-bit polynomial
multiplication by adding support for 4-way aggregation. This
more than doubles the performance, from 2.4 cycles per byte
to 1.1 cpb on Cortex-A53.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Checking the TIF_NEED_RESCHED flag is disproportionately costly on cores
with fast crypto instructions and comparatively slow memory accesses.

On algorithms such as GHASH, which executes at ~1 cycle per byte on
cores that implement support for 64 bit polynomial multiplication,
there is really no need to check the TIF_NEED_RESCHED particularly
often, and so we can remove the NEON yield check from the assembler
routines.

However, unlike the AEAD or skcipher APIs, the shash/ahash APIs take
arbitrary input lengths, and so there needs to be some sanity check
to ensure that we don't hog the CPU for excessive amounts of time.

So let's simply cap the maximum input size that is processed in one go
to 64 KB.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Fixes: 915e4e84 ("crypto: hisilicon - SEC security accelerator driver")
Signed-off-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Variable esign is being assigned but is never used hence it is
redundant and can be removed.

Cleans up clang warning:
warning: variable 'esign' set but not used [-Wunused-but-set-variable]
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Squeeze out another 5% of performance by minimizing the number
of invocations of kernel_neon_begin()/kernel_neon_end() on the
common path, which also allows some reloads of the key schedule
to be optimized away.

The resulting code runs at 2.3 cycles per byte on a Cortex-A53.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Implement a faster version of the GHASH transform which amortizes
the reduction modulo the characteristic polynomial across two
input blocks at a time.

On a Cortex-A53, the gcm(aes) performance increases 24%, from
3.0 cycles per byte to 2.4 cpb for large input sizes.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Update the core AES/GCM transform and the associated plumbing to operate
on 2 AES/GHASH blocks at a time. By itself, this is not expected to
result in a noticeable speedup, but it paves the way for reimplementing
the GHASH component using 2-way aggregation.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Merge crypto-2.6 to pick up NEON yield revert.

As it turns out, checking the TIF_NEED_RESCHED flag after each
iteration results in a significant performance regression (~10%)
when running fast algorithms (i.e., ones that use special instructions
and operate in the < 4 cycles per byte range) on in-order cores with
comparatively slow memory accesses such as the Cortex-A53.

Given the speed of these ciphers, and the fact that the page based
nature of the AEAD scatterwalk API guarantees that the core NEON
transform is never invoked with more than a single page's worth of
input, we can estimate the worst case duration of any resulting
scheduling blackout: on a 1 GHz Cortex-A53 running with 64k pages,
processing a page's worth of input at 4 cycles per byte results in
a delay of ~250 us, which is a reasonable upper bound.

So let's remove the yield checks from the fused AES-CCM and AES-GCM
routines entirely.

This reverts commit 7b67ae4d and
partially reverts commit 7c50136a.

Fixes: 7c50136a ("crypto: arm64/aes-ghash - yield NEON after every ...")
Fixes: 7b67ae4d ("crypto: arm64/aes-ccm - yield NEON after every ...")
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Make it return -EINVAL if crypto_dh_key_len() is incorrect rather than
overflowing the buffer.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

It was forgotten to increase DH_KPP_SECRET_MIN_SIZE to include 'q_size',
causing an out-of-bounds write of 4 bytes in crypto_dh_encode_key(), and
an out-of-bounds read of 4 bytes in crypto_dh_decode_key().  Fix it, and
fix the lengths of the test vectors to match this.

Reported-by: syzbot+6d38d558c25b53b8f4ed@syzkaller.appspotmail.com
Fixes: e3fe0ae1 ("crypto: dh - add public key verification test")
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Should the PSP initialization fail, the PSP data structure will be
freed and the value contained in the sp_device struct set to NULL.
At module unload, psp_dev_destroy() does not check if the pointer
value is NULL and will end up dereferencing a NULL pointer.

Add a pointer check of the psp_data field in the sp_device struct
in psp_dev_destroy() and return immediately if it is NULL.

Cc: <stable@vger.kernel.org> # 4.16.x-
Fixes: 2a6170df ("crypto: ccp: Add Platform Security Processor (PSP) device support")
Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
Acked-by: NGary R Hook <gary.hook@amd.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The 4-way ChaCha20 NEON code implements 16-bit rotates with vrev32.16,
but the one-way code (used on remainder blocks) implements it with
vshl + vsri, which is slower.  Switch the one-way code to vrev32.16 too.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The ccree driver had a sanity check that we are not asked
to encrypt an XTS buffer bigger than a sane sector size
since XTS IV needs to include the sector number in the IV
so this is not expected in any real use case.

Unfortunately, this breaks cryptsetup benchmark test which
has a synthetic performance test using 64k buffer of data
with the same IV.

Remove the sanity check and allow the user to hang themselves
and/or run benchmarks if they so wish.
Reported-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NGilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

In certain error path req_ctx->iv was being freed despite
not being allocated because it was not initialized to NULL.
Rather than play whack a mole with the structure various
field, zero it before use.

This fixes a kernel panic that may occur if an invalid
buffer size was requested triggering the bug above.

Fixes: 63ee04c8 ("crypto: ccree - add skcipher support")
Reported-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NGilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

IV generation is not available via the skcipher interface.
Remove the left over support of it from the ablkcipher days.
Signed-off-by: NGilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Drop the explicit setting of CRYPTO_ALG_TYPE_AEAD or
CRYPTO_ALG_TYPE_SKCIPHER flags during alg registration as they are
set anyway by the framework.
Signed-off-by: NGilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Like the skcipher_walk and blkcipher_walk cases:

scatterwalk_done() is only meant to be called after a nonzero number of
bytes have been processed, since scatterwalk_pagedone() will flush the
dcache of the *previous* page.  But in the error case of
ablkcipher_walk_done(), e.g. if the input wasn't an integer number of
blocks, scatterwalk_done() was actually called after advancing 0 bytes.
This caused a crash ("BUG: unable to handle kernel paging request")
during '!PageSlab(page)' on architectures like arm and arm64 that define
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE, provided that the input was
page-aligned as in that case walk->offset == 0.

Fix it by reorganizing ablkcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.
Reported-by: NLiu Chao <liuchao741@huawei.com>
Fixes: bf06099d ("crypto: skcipher - Add ablkcipher_walk interfaces")
Cc: <stable@vger.kernel.org> # v2.6.35+
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Like the skcipher_walk case:

scatterwalk_done() is only meant to be called after a nonzero number of
bytes have been processed, since scatterwalk_pagedone() will flush the
dcache of the *previous* page.  But in the error case of
blkcipher_walk_done(), e.g. if the input wasn't an integer number of
blocks, scatterwalk_done() was actually called after advancing 0 bytes.
This caused a crash ("BUG: unable to handle kernel paging request")
during '!PageSlab(page)' on architectures like arm and arm64 that define
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE, provided that the input was
page-aligned as in that case walk->offset == 0.

Fix it by reorganizing blkcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.

This bug was found by syzkaller fuzzing.

Reproducer, assuming ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE:

	#include <linux/if_alg.h>
	#include <sys/socket.h>
	#include <unistd.h>

	int main()
	{
		struct sockaddr_alg addr = {
			.salg_type = "skcipher",
			.salg_name = "ecb(aes-generic)",
		};
		char buffer[4096] __attribute__((aligned(4096))) = { 0 };
		int fd;

		fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
		bind(fd, (void *)&addr, sizeof(addr));
		setsockopt(fd, SOL_ALG, ALG_SET_KEY, buffer, 16);
		fd = accept(fd, NULL, NULL);
		write(fd, buffer, 15);
		read(fd, buffer, 15);
	}
Reported-by: NLiu Chao <liuchao741@huawei.com>
Fixes: 5cde0af2 ("[CRYPTO] cipher: Added block cipher type")
Cc: <stable@vger.kernel.org> # v2.6.19+
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

scatterwalk_done() is only meant to be called after a nonzero number of
bytes have been processed, since scatterwalk_pagedone() will flush the
dcache of the *previous* page.  But in the error case of
skcipher_walk_done(), e.g. if the input wasn't an integer number of
blocks, scatterwalk_done() was actually called after advancing 0 bytes.
This caused a crash ("BUG: unable to handle kernel paging request")
during '!PageSlab(page)' on architectures like arm and arm64 that define
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE, provided that the input was
page-aligned as in that case walk->offset == 0.

Fix it by reorganizing skcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.

This bug was found by syzkaller fuzzing.

Reproducer, assuming ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE:

	#include <linux/if_alg.h>
	#include <sys/socket.h>
	#include <unistd.h>

	int main()
	{
		struct sockaddr_alg addr = {
			.salg_type = "skcipher",
			.salg_name = "cbc(aes-generic)",
		};
		char buffer[4096] __attribute__((aligned(4096))) = { 0 };
		int fd;

		fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
		bind(fd, (void *)&addr, sizeof(addr));
		setsockopt(fd, SOL_ALG, ALG_SET_KEY, buffer, 16);
		fd = accept(fd, NULL, NULL);
		write(fd, buffer, 15);
		read(fd, buffer, 15);
	}
Reported-by: NLiu Chao <liuchao741@huawei.com>
Fixes: b286d8b1 ("crypto: skcipher - Add skcipher walk interface")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Setting 'walk->nbytes = walk->total' in skcipher_walk_first() doesn't
make sense because actually walk->nbytes needs to be set to the length
of the first step in the walk, which may be less than walk->total.  This
is done by skcipher_walk_next() which is called immediately afterwards.
Also walk->nbytes was already set to 0 in skcipher_walk_skcipher(),
which is a better default value in case it's forgotten to be set later.

Therefore, remove the unnecessary assignment to walk->nbytes.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

scatterwalk_samebuf() is never used.  Remove it.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

All callers pass chain=0 to scatterwalk_crypto_chain().

Remove this unneeded parameter.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The ALIGN() macro needs to be passed the alignment, not the alignmask
(which is the alignment minus 1).

Fixes: b286d8b1 ("crypto: skcipher - Add skcipher walk interface")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Enable all 4 SEC units available on d05 boards.
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This accelerator is found inside hisilicon hip06 and hip07 SoCs.
Each instance provides a number of queues which feed a different number of
backend acceleration units.

The queues are operating in an out of order mode in the interests of
throughput. The silicon does not do tracking of dependencies between
multiple 'messages' or update of the IVs as appropriate for training.
Hence where relevant we need to do this in software.
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The hip06 and hip07 SoCs contain a number of these crypto units which
accelerate AES and DES operations.
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Avoid RCU stalls in the case of non-preemptible kernel and lengthy
speed tests by rescheduling when advancing from one block size
to another.
Signed-off-by: NHoria Geantă <horia.geanta@nxp.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

__virtio_crypto_ablkcipher_do_req() is never called in atomic context.

__virtio_crypto_ablkcipher_do_req() is only called by
virtio_crypto_ablkcipher_crypt_req(), which is only called by
virtcrypto_find_vqs() that is never called in atomic context.

__virtio_crypto_ablkcipher_do_req() calls kzalloc_node() with GFP_ATOMIC,
which is not necessary.
GFP_ATOMIC can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.
I also manually check the kernel code before reporting it.
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

adf_dev_aer_schedule_reset() is never called in atomic context, as it
calls wait_for_completion_timeout().

adf_dev_aer_schedule_reset() calls kzalloc() with GFP_ATOMIC,
which is not necessary.
GFP_ATOMIC can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.
I also manually check the kernel code before reporting it.
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

crypto_alloc_context() is only called by nitrox_skcipher_init(), which is
never called in atomic context.

crypto_alloc_context() calls dma_pool_alloc() with GFP_ATOMIC,
which is not necessary.
GFP_ATOMIC can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.
I also manually check the kernel code before reporting it.
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>